The present disclosure relates to a battery cell monitoring unit for monitoring battery cells and to a method for fault detection and elimination in a battery cell monitoring unit. Furthermore, the disclosure relates to a battery system comprising a battery cell monitoring unit and to a motor vehicle comprising the battery system.
In electrically driven vehicles, lithium-based accumulators or batteries are frequently used since these have a high energy density. In this arrangement, a battery pack is constructed of a number of battery modules which themselves, in turn, consist of the individual lithium battery cells. Due to their operation and the materials used, lithium accumulators require careful control and monitoring both during charging and during discharging. This task is usually handled by a battery management unit. Known battery management units consist of a battery control unit and a battery cell monitoring unit per battery module. Conventional battery cell monitoring units contain an integrated measuring chip, temperature sensors and resistors for balancing the battery cells. Such measuring chips, e.g. the TI bq76PL536 chip, measure voltages of a number of battery cells and their temperature and have for this purpose an analog/digital converter and a multiplexer which switches the various battery cell voltages, voltages from temperature sensors and a reference voltage through to the analog/digital converter. Such an analog/digital converter generates a sequence of measurement data which reproduce the battery cell voltages and temperatures.